I respectfully disagree with you here. The beauty and the wonder of these small command line tools (for me, at least) is that they are a) small and b) fast and c) ubiquitious. I do a lot of data manipulation, and while I'll do anything complex in a real programming language (with a REPL) sed, awk, grep and find are really really handy for quick data finding and manipulation.

Any new API on top of them would only be present on a fraction of machines, and thus would reduce the major advantage of them in that they are available everywhere.